Method of treating impure bismuth metal.



UNITED STATES PATENT OFFICE.

WALTER C. SMITH, OF CHROME, NEW JERSEY, ASSIGNOR T0 UNITED STATES METALS REFINING COMPANY, OF CHROME, NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF TREATING IMPURE BISMUTH METAL.

No Drawing.

0 all whom it may-concern Be it known that I, IVALTER C. SMITH, a citizen of the; United States, residing at Chrome, in the county of Middlesex and State of New Jersey, have invented certain new and useful Improvements in Methods of Treating Impure Bismuth Metal; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to makeand use the same.

The invention relates to a method or process of treating bismuth bearing ores or metallurgical products containing bismuth for the recovery of the metallic bismuth contained therein.

The object of the invention is to provide a novel and improved method or process which will enable a high percentage of the bismuth contained in the materials treated to be recovered, more economically, and of greater purity than heretofore.

To this end the invention consists in the method or process, and the steps and subduced to metal and concentrated by any suitable metallurgical method. The impure bismuth metal thus obtained may contain various kinds of impurities, and the. method of treating the metal which is best suited to recover the bismuth in the desired state of purity may vary with the impurities present and the extent to which the purification is to be carried. The complete method or process which is adapted for the economical elimination of all the impurities Which are likely to be present in any bismuth metal comprises four principal steps or methods of treatment which may be performed in any desired order. If certain impurities are not present in the bismuth which is to be treated. then one or more of the steps may be omitted with advantage, and the purification of the metal be completed or carried to the desired extent by the other step or steps or methods of treatment. In treating the bismuth metal with the four steps or methods of treatment comprising the completeprocess, certain im purities may be completely or partially removed by the first treatment which would also be completely or partially removed by Specification of Letters Iatent.

Patented Jan. 4, 1916.

one of the subsequent treatments if present in the metal being treated. In such case the removal of certain impurities may be effected fractionally by the successive treatments, and the different steps may be combined to secure that fractional removal of the impurities which is the most eflicient and economical.

In further explaining the invention, reference will first be made to each of the four steps or methods of treatment. and its effect on the bismuth metal, under the assumption that the metal has not been previously treated by any of the other steps or methods of treatment.

In accordance with one of the steps or methods of treatment, sulfur is added to the metal while the metal is in a molten condition, and the metal is preferably agitated to bring the sulfur in contact with the various impurities which are distributed through the molten material. The sulfur may be in the form of native sulfur, brimstone, flowers of sulfur, sulfids, or a mixture of sulfates and carbon. The effect of the treatment with sulfur is to separate nearly all of the copper, the greater proportion of the tellurium, silver, arsenic, antimony, selenium and zinc, some of the tin, and a fair proportion of the lead which may be present in the metal. None of the gold is removed by this treatment. The impurities specified unite with the sulfur and form a sort of matte which is a combination of the metals with the sulfur as sulfids. This matte floats on the surface of the molten metal and may be skimmed off. The removal of the impurities is more effectively done by lowering the temperature of the molten metal, after the addition of the sulfur, to a temperature of about 515 to 520 F. This treatment may be repeated until by test the bismuth is shown to be substantially free from the impurities which man-ah,

impurities throughout the molten nr-iss h stirring or agitating the molten metal prrl'rrably hr the us. ol strain The eausii soda or other :illvali arts I =5 [he ivlhn'inni. selenium. sullur. :irseniw. anliinoiri. tin and zine which may he prewnt in the metal, training sodium rompounils whieli lloai on the surface of the metal. and may be removed troin the purified inrlal y skimming or ther means. The operation not; he repeated until by test the metal shun the rt moval of substantiallv all oi" the impurities referred to. or the alkali treatment may be utilized to pert ert :1 t'rartioual removal ol the impurities. or to substantially eoniplete the removal of impurities whieh have been fraetionally removed by other treatment.

In arrorllanre with another step or HitlllUil of treatment. Zllir is dissolved in the his muth metal while it is in a molten eomlition. and the molten bath is prefera ly thoroughly stirred. The zine unites with the telluriuni. copper, old silver, selenium. arsenie. antimun and tin which may he in the metal to form alloys which lloat upon the surface of the metal and may be removed. The separation of the Zine alloys is tai'rilitated by lowering the temperature oi the molten bath to about Infill l. alter the zine has been eon1- pletely dissolved and thoroughly stirred into the molten bath. The lowerim; of the. temperature does not remove all of the zine, but the quantit whieh remains may not he detrimental to the quality of the bismuth for certain uses to which it may be put. It it is desired, however. to produce a bismuth whieh is free from nine, the temperature of the bath may be raised, and the Zine maybe eliminated by treating the molten bath with caustic soda or othe alkali. This method of treatment may also be'utilized to remove substantially all the im 'mrities enumerated. or may he used in eonibination with the other steps of the proeess in seruring a frartional iemoval of the impurities when by such treatment the impurities may be more e00- nomieally removed.

In aeeordanee with another step or method of treatment, the impure bismuth metal is brought into a molten condition. and then the temperature is lowered until crystallization of the bismuth begins. The artion of crystallization is to separate pure or sub stantially pure bismuth as crystals from the impurities which remain in solution. The molten metal is kept at suelra temperature that the erystallization continues. and dnr ing the crystallization the metal may be stirred with air. steam or other means. and the purity of the crystals henetitted thereby. This action is a partial separation, sinee the molten liuuid which remains al ter the crystals have been removed is a mixture of bismuth and the impurities, while the crystals may be substantially pure bismuth.

ti ler one batrh ol' ri'ystals has been re.- ifl l l. the rrvslallimtion may e allowed t lll'lilltll lurill r. and another l 'llll'll ol' rv tals removed. During thew siuwessive operations the ervstals llliUllli less pure. While the impurity ol' the molten remaining portions inrreases through the vonrenlration ol' the impurities in the mass. The impure rrystals ma) be further purilievl. or the his nuuh removed fr m the iniplire residue. by lreatinenl, in :u-i-orilunre with any or all of the steps or methods oi treatment previously mentioned.

The advantage of utilizing the proress romprising the four steps or na-thoils of treatment enunu-rated iu (tier-ting a tram tioual and sureessive separation of the inr purities may best be explained y eonsicler lug the lll'lNt'rS in runner-lion with the tr at uu-nt ol' an impure hisnuith metal rontaiuine substantially all the impurities enumerated. l n uvplainin; this treatnirnt it will be as sumed that the steps are lierlornu-cl in the order in Willtl! they have been referred to. although it will he understood. as alreavlv stated. that this order is not essential. and is seleeted for the purpose ol' explanation.

Alter the treatment with sullnr. and re moval of the impurities separat d therelu in the manner above. desrrihed, the bismuth metal will he praetirallv tree from eopper. may rontain :1 part of the tellurium and :1 somewhat greater proportion of the lead. a small proportion of the silver and sulfur. all the gold, and will be praetieally tree from autimouv and arsenic. The subsequent treatment with raustie soda will remove the remaining tellurium and sulfur and slightly reduee the amount of lead. The silver and gold will be unaffected. The treatment with ZlIH' will not atl'ert the leaih will further re- (llic'c the silver. and will remove substantially all the. gold. The remaining lead, and praw tirail all the remainin f silver and an} gold whieli may remain after the zine treatment. will be removed by the crystallization.

If the impure bismuth metal did not carry any lead, the step of crystallization might. be omitted with advantage, the treatment with zinc being married further. or until practically all the gold and silver had been removed. Ill there is lead present. however. the zine treatment may be stopped before all the gold and silver are removed. since they will be removed with the lead in the ervstallization treatment. This is referred to as an example of conditions under which a sulvproeess or part of the complete proees, may he used with advantage.

Other nmdilirations in the process. or in the steps or methods of treatment to whieh the metal is subjeeted, may be made in ac eordanee with the impurities of eharaeter of the metal to be treated.

Vl hile, as above explained, the order in lie) treatment with caustic soda or otheralkali should precede the zincing treatment when the impure metals contain sulfur, tellurium or selenium, since these elements require a large amount of zinc to be used before the zinc alloys with the gold and silver, thus increasing the cost of treatment.

Having explained the nature and object of the invention, and specifically described the manner in which it may be practised, what is claimed is 1. The method of treating impure bismuth metal or metals containing a high percentage of bismuth, cgmprising'subjecting the molten metal to the action of sulfur and removing the impurities separated thereby, subjecting the molten metal to the action of an alkali as caustic soda and removing the impurities separated thereby, dissolving zinc in the molten metal and removing the impurities separated thereby, bringing the metal to a molten condition, then lowering the temperature until crystallization begins, and removing the crystals of purified bismuth thus formed.

2. The method of treating impure bismuth metal or metals containing a high percentage of bismuth consisting in subjecting the molten metal to the action of sulfur and removing the impurities separated thereby, subjecting the molten metal to the action of an alkali and removing the impurities separated thereby, dissolving zinc in the molten metal and removing the impurities separated thereby, bringing the metal to a molten condition and treating with an alkali and removing the impurities separated thereby, then lowering the temperature of the molten mass until crystallization takes place, and removing the crystals of purified bismuth thus formed.

3. The method of treating impure bismuth metal or metals containing a high percentage of bismuth, consisting in subjecting the molten metal to the action of an alkali and removing the impurities separated thereby.

4:. The method of treating a high ercentage bi smuth metal carrying impurlties of copper; lead, tellurium, silver, gold, arsenic and antimony, etc., comprising melting the metal, treating with sulfur and skimming to eliminate the greater portion of the arsenic, antimony and copper, maintaining the residue in a molten state, treating with caustic soda and skimming to eliminate the tellurium, arsenic, antimony and sulfur remaining from the prior treatment, maintaining the resulting residue in a molten state, dissolving zinc therein, cooling and skimming toeliminate copper, gold and silver, melting the gold-free residue,

treating with caustic soda and skimming to eliminate any remaining 'zinc'and melting and then cooling the residue to crystallize the substantially free bismuth and separate it from the lead.

5. The method of treating impure bismuth metal ormetals containing a high percentage of bismuth, consisting in bringing the metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing from the molten mixture the crystals of bismuth so formed.

6. The method of treating impure bismuth metal or metals containing a hi h percentage of bismuth, consisting in su jecting the molten metal to the action of caustic soda and removing the impurities separated thereby.

7. The method of treating a high percentage bismuth metal carrying impurities of tellurium, selenium, sulfur, zinc, etc., comprising melting the metal, treating with caustic soda, mixing the treated mass with superheated steam and skimming the mixed mass to remove sodium compounds of the tellurium, sulfur, selenium and zinc carried by the impure metal.

8. The method of treating impure bismuth metal or metals containing a high percentage of bismuth, comprising dissolving zinc in the moltenmetal, removing the alloys formed between the zinc and the impurlties in the metal, and subjecting the ismuth metal thus purified to the action of an alkali as caustic soda to remove the unalloyed zinc.

9. The method. of treating impure bismuth metal or metals containing a hi h percentage of bismuth, consistirig in su jeoting the molten metal to the action of sulfur, removing the impurities separated thereby, subjecting the molten metal to the action of an alkali as caustic soda, and removin the im urities separated thereby.

10. he met od of treating impure bis- 10 muth metal or metals containing a high percentage of bismuth, consisting in sub jecting the molten metal to the action of sulfur, removing the impurities separated thereby, dissolving zinc in the molten metal, and removing the alloys formed between the zinc and the impurities in the molten metal.

11. The method of treating impure bismuth metal or metals containing a high percentage of bismuth, consisting in subjecting the molten metal to the action of sulfur, removin the impurities separated thereby, bringmg the metal to a molten condition, lowering the temperature -until the material begins to crystallize, and removing from the molten mixture the-bismuth crystals so formed.

12. The method of treating impure bismuth metal or metals containing a high percentage of bismuth, consisting in subjecting the molten metal to the action of an alkali as caustic soda, removing the impurities separated thereby, dissolving zinc in the molten metal, and removing the alloys formed between the zinc and the impurities in the molten metal.

' 13. The method of treating impure bismuth metal or metals containing a high per centage of bismuth, consisting in subjecting the molten impure metal to the action of an alkali as caustic soda, removing the impurities separated thereby, bringing the metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing the bismuth crystals so formed. 7

14. The method of treating impure bismuth metal or metals containing a high percentage of bismuth, consisting 1n dissolving zinc in the molten metal, removing the alloys formed between the zinc and the impurities in the metal, bringingthe metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing the bismuth crystals so formed' 15. The method of treating impure bis-,

muth metal or metals containing a high percentage of bismuth, consisting in sub ecting the molten metal to the action of sulfur, re-.

moving the impurities separated thereby, subjecting the molten metal to the action of an alkali as caustic soda, removing the impurities separated thereby, dissolving zinc in the molten metal, and removing the alloys formed between the zinc and the impurities in the molten metal.

16. The method of treatingimpure bismuth metal or metals containing a high percentage of bismuth, consisting in subjecting the'molten metal to the action of sulfur, removing the impurities separated thereby, subjecting the molten metal to the action of an alkali as caustic soda, removing the impurities separated thereby, bringing the metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing the crystals of bismuth so formed. w

17. The method of treating impure bismuth metal or meta-ls containing a high percentage of bismuth, consisting in subjecting the molten metal to the action of sulfur, removing the impurities separated thereby, dissolving zinc in the molten metal, removing the alloys formed between the zinc and impurities in the metal, bringing the metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing the bismuth crystals so formed.

18. The method of treating im ure bismuth metal or metals containing a igh percentage of bismuth, consistingin SUbJQCtiIIg the molten metal to the action of an alkali as caustic soda, removing the impurities separated thereby, dissolving zinc in the molten metal, removing the alloys formed between the zinc and impurities in the metal, bringing the metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing the bismuth crystals so formed.

WALTER 0. SMITH. Witnesses:

GRACE FITCH SMITH, J. 'E. HASLAM.

and removing:'the bismuth crystals so formed.

15. The method 'ofhtreating impure bis,

muth metal or metalscontaininga high percentage of bismuth, consisting in subjecting the inolten metal to the action of sulfur, re-. moving the impurities separated. thereby, subjecting the molten metal to the action of an alkali as caustic soda, removing the impurities separated thereby, dissolving zinc in the molten metal, and removing the alloys the'molten metal to the action of an alkali as caustic soda, removing the impurities separated thereby, dissolving zinc in the molten metal, removing the alloys formed between the zinc and impurities in the metal, bringing the metal to a molten condition, lowering the temperature until the material begins to crystallize, and removing the his- -muth crystals so formed.

WALTER 0. SMITH.

formed between the zinc and the impurities Witnesses: in the molten. metal. v I GRACE FITCH SMITH,

16. The method of treatingimpure bis- J. E. HASLAM.

centage of bismuth, consisting in subjecting muth metal or metals containing a high per 40 the molten metal to the action of an alkali centage of bismuth, consisting in subjecting as caustic 'soda, removing the impurities the'molten metal to the action of sulfur, reseparated thereby, dissolving zinc in the moving the impurities separated thereby, molten metal, and removing the alloys subjecting the molten metal to the action of formed between the zinc and the impurities an alkali as caustic soda, removing the imin the molten metal. purities separated thereby, bringing the 13. The method of treating impure bismetal to a molten condition, lowering the muth metal or metals containing a high per-' temperature until the material begins to centage of bismuth, consisting in subjecting crystallize, and removing the crystals of the molten impure metal to the action of an. bismuth so formed. I alkali as caustic soda, removing the impuri- .17. The method of treating impure bisties separated thereb' bringing the metal muth metal or metals containing a high per- 'to a molten condition, lowering the temcentage-of bismuth, consisting in subjecting perature' until the material begins to crysthe molten metal to the action of sulfur, re-

tallize, and removing the bismuth crystals moving the impurities separated thereby, so formed. dissolving zinc in the molten metal, remov- 1.4. The method of treating impure bis,- 'ing the alloys formed between the zinc and muth metal or metals containing a high per-- impurities in the metal, bringing the metal centage of bismuth, consisting in dissolving to a molten condition, lowering the temzinc in the molten metal, removing the alperature until the material begins to crys- B0 loys formed between the zinc and the imtallize, and removing the bismuth crystals purities in the metal, bringingthe metal to so formed. j 4 a molten conditiomlowering the tempera- 18. The method oftreating impure bis- 2 mm until the material begins to crystallize, muth metal-or metals containing ahigh percentage of bismuth, consisting in subjecting "is hereby certified that inLetters Patent N 0. 1,166,721, grantedJanuary 4,

'-I 9l6, up on the application of Walter C. Smith, of- Chrome', New Jersey, fo'r an improvement in Methods of Treating Impure Bismuth Metal, errors appear. in I the printed specification requiring correction as follows" Page 2, line 23", strike o'ut theword told and insertithe word golcl and a. comma, same page, Line 128, for the word of, first b lccui'rence, read or; aml that the said Lettersj'Patent should be read with the'se correctionstherein that the' same may conformrto the Letters Patent No. 1 166,721

.record of the ease in the'i atent Ofiice; v I Signed' andsealed this is day at February, A, 1)., 191a. r 1' [HEAL] p 7 4 I J. T. NEWTON,

. i am oommamqrmu.

Correbtiohs in 'It is hereby certified that in Letters Patent No. 1,166,721, granted January 4,

1916, upon the application of Walter C. Smith, of Chrome, New Jersey, for an improvement in Methods of Treating Impure Bismuth Metal, errors appear in the printed specification requiring correction as follows: Page 2, line 23 strike out the word old and insert the word gold and a comma; same page, line 128, for the word of, first occurrence, read or; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflioe.

Signed and sealed this 1st day of February, A. D., 1916.

[mun] J. T. NEWTON,

Acting Commissioner of Patents. 

